module RESTng.System.Resource (
                          module RESTng.System.Proxy,
                          OwnerId, SystemFields,
                          Resource,
                          resourceType, key, setKey, keyName,
                          ownable, ownerId, setOwnerId, ownerIdName,
                          userFields,
                          nonKeyFields, userFieldsWithKey
                         ) where

import RESTng.System.Proxy

type OwnerId = Integer
type SystemFields = (Integer, Maybe OwnerId)
    
class Resource a where
  resourceType :: Proxy a-> String

  key :: a -> Integer
  setKey :: a -> Integer -> a
  keyName :: Proxy a -> String; keyName _ = "id"

  ownable :: Proxy a -> Bool; ownable _ = False
  ownerId :: a -> OwnerId
  setOwnerId :: OwnerId -> a -> a
  ownerIdName :: Proxy a -> String; ownerIdName _ = "owner_id"

  userFields :: Proxy a -> [String]


------------------------------------
-- Serializing to text. (records) --
------------------------------------
nonKeyFields :: Resource a => Proxy a -> [String]
nonKeyFields pr = if ownable pr
                    then ownerIdName pr : userFields pr
                    else userFields pr


userFieldsWithKey :: Resource a => Proxy a -> [String]
userFieldsWithKey r = keyName r : userFields r